2 Samuel 18:5-7

The king charged Joab and Abishai and Ittai, saying, “Deal gently for my sake with the young man Absalom.” And all the people heard when the king charged all the commanders concerning Absalom. Then the people went out into the field against Israel, and the battle took place in the forest of Ephraim. The people of Israel were defeated there before the servants of David, and the slaughter there that day was great, 20,000 men.